Revealing Enhanced Optoelectronic Performance of Sb₂Se₃‐Based Self‐Sustaining Heterostructures with Bi₂Se₃ and ZnSe: A Dual Polarity Photo Response

Abstract Through precise band engineering, Van der Waals heterostructures integration holds great promise for advancing high‐performance optoelectronic devices, especially photodetectors. This study presents self‐sustaining, dual‐polarity, high photo‐responsive heterostrutures (HS) photodetectors based on Sb₂Se₃, specifically Bi₂Se₃/Sb₂Se₃ and ZnSe/Sb₂Se₃. The Bi₂Se₃ (ZnSe) layer functions as a channel in a reconfigurable HS phototransistor configuration. These HS devices demonstrate a negative photoconductive response with bias‐modulated polarity switching of the photocurrent. The Bi₂Se₃/Sb₂Se₃ device exhibits a responsivity switch from −4 mA W⁻¹ to 0.14 A W⁻¹, while the ZnSe/Sb₂Se₃ device shows a substantially enhanced responsivity switch from ‐400 mA W⁻¹ to 12 A W⁻¹. This negative photo response results from a photoinduced carrier trapping mechanism at the interface of the channel layer and photosensitizer material. The bias modulation enables the switching from negative to positive responsivity. A comprehensive investigation of photoconductivity modulation provides a deeper understanding of the impact of the photogating effect and trap states under applied bias conditions. Ultrafast transient spectroscopy supports these findings, offering insights into the dynamics of charge carrier relaxation mechanisms and the trapping of photoexcited carriers in defect states, crucial for explaining the dual polarity photo response. These devices present significant advantages for switchable light imaging, optical communication, memory devices, convolution processing, and logic circuits.